<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>过渡动画</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            background: red;
            transition-property: with;
            transition-duration: 1s;
            transition-timing-function:linear;
            transition-delay: 1s;
            /*Safari*/
            -webkit-transition-property: width;
            -webkit-transition-duration: 1s;
            -webkit-transition-timing-function:linear;
            -webkit-transition-delay: 1s;
        }
        div:hover{
            width: 500px;
        }
    </style>
</head>
<body>

<div></div>
</body>
</html>